In aeronautics, the neutral state commonly used is the TN-C state, which means:                T: neutral of the installation connected directly to the ground,        N: masses of the installation connected to the neutral conductor,        C: protective conductor for the masses of the installation and neutral conductor combined.        
In an electrical power supply system onboard an airplane, the neutral of each primary generator G is connected to the fuselage 10′ of the airplane, at the engine pylons (1 meter of cable) in order to ensure the return of the unbalance current and faults. Furthermore, all of the masses of the equipment are connected to said fuselage. The fuselage therefore plays the role both of neutral and ground conductor. FIG. 1 thus shows a three-phase generator G, the neutral N of which is connected to the fuselage 10′, connected to an electric core 11′ by its phases ph1, ph2 and ph3, a phase-to-ground fault charge 12′ whereof the mass is connected to the fuselage 10′. A fault current id 13′ relative to this fault charge 12′, which passes toward the fuselage 10′, is also illustrated.
In such a configuration, the primary generators G perform the functions of the direct, reverse, and homopolar current component generators for example described in the document referenced [1] at the end of the description.
The neutral state as defined above makes it possible to achieve a significant mass gain while avoiding the addition of extra cables. However, the distribution of the neutral of the primary generators G causes an excess weight for two reasons:                The connection of the neutral of each generator G to the fuselage allows the circulation of the harmonic 3 currents, i.e. the circulation of homopolar currents, which causes additional losses. To greatly reduce the value of these harmonic 3 currents, it is possible to use generators designed with a ⅔ pitch winding structure, which involves a slight attenuation of the fundamental. Consequently, the power-weight ratio of the generator decreases.        
In the case of an airplane whereof the fuselage is made from carbon, the neutral of each generator G cannot be connected to the engine pylon. It is connected to the PVR (“Point Voltage Reference”) of the ESN (“Electrical Structural Network”) 10, as illustrated in FIG. 2. The neutral and the mass of the charges are connected to the ESN.
The location of the primary generators G in the wings of an airplane 20 near each engine 21 and that of the electric cores 22 at the front of the airplane requires a non-negligible neutral cable length 23, as illustrated in FIG. 3, such an “electric core” being a source—charge interconnect node including protective and contact members, the voltage of which is stabilized by an outside element. This results in a significant power-weight ratio in the case where the airplane 20 has four electric power supply channels, and therefore four neutral cables.
The invention aims to eliminate such neutral cables in order to decrease the volume and mass of the electrical power supply on-board the airplane, the primary generators keeping the role of generators of the direct and reverse components, but the homopolar generator function being performed by a specific piece of equipment.